Fuel injection means for free piston engines



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FUEL INJECTION MEANS FOR FREE PISTON ENGINES Filed Aug. 4, 1944 A 10 Sheets-Sheet 4 l J'E"'7'l T-lm IEE y 7///// l f '7L/g 7 5;/

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' FUEL INJECTION MEANS FOR FREE PISTON ENGINES Filed Aug. 4, 1944 10 Sheetanhest/T 24, 1948. F. M. LEWIS U 2,447,5I3

FUEL INJECTION IIEANS FOR FREE PIS'ION ENGINES Filed Aug'. 4, 1944 l 10 Sheets-$heet 8 FRANK M LEM/f5 Aug. 24, 1948. F. M. LEwls 2,447513 rum.. rumanos mams Fon man Pxsrou nnenms Filed Aug. 4, 1944 4 1o sheets-sheet 9` Rebnqnce Pressure Compsxhm Bressuire 3mm EIMNK .MLB 5 Aug. 24,1948. F. M. LEwIs 2,447,513

FUEL' INJECTION IIEANS FOR P REE PISTH ENGINES Filed Aug. 4. 1944 1o sheets-sheet 1o i .FANK MLM/'z5 ai, w-nba-wo, 1 i GW Patented Aug.v 24, 1948 INJECTION MEANS FOR FREE PISTON ENGINES Frank M. Lewis, Weston, Mass.. lassignor, by

mesne assignments, to Lima-Hamilton Corporation, Hamilton, Ohio, a corporation of Virginie Application August 4; m4, serial No. 548,116

(el. 12s-4c) v 21 Claims.

This invention relates to fuel injection means and methods for internal.` combustion engines. and particularly to a fuel pump operable in conjunction with the fuel injection systems of such engines of thefree piston type.

In the running of engines of this type. the positions attained by the pistons at the Ycombustion end of a stroke, when fuel is to be injected, will vary with the load and the speed. Therefore, if a type of fuel linjector is usedin which injections occur when the piston reaches a certain point in the cylinder, this variation in stroke introduces undesirable variation in the timing of injections of the fuel with reference to the combustion end of the stroke, so that the injection may occur too early, too late or possibly not at all. A very small portion of the piston motion at the end of the stroke is available to effect the injection, and this introduces serious mechanical difiiculties in the drive of such a pump.

The object of the invention is to obviate the above-noted objections by the provision of means which is operable by a running of a free piston engine to time the fuel injections by the relation of the piston to the end of its compression stroke,

regardles of how the length of the stroke may vary with variations of the load and speed of the engine.

Anothefobject of the invention is the provision of a fuel pump for free piston engines which in its operation will utilize a large part of the piston stroke of the engine to pump fuel, thus obviating the mechanical dimculties abovementioned.

Another object of the invention is the provision in connection with an internal combustion engine of the free piston type, of fuel injection means therefor. wherein the timing of fuel injections is determined primarily by the change of speed of the engine pistons as they near the ends of their compression strokes.

piston type in accordance with the engine speed by utilizing, in part at least, pressures generated in the combustion and rebounce chambers of the engine or in either one of them.

Further objects and advantages of the invention will be apparent from the following detailed `description and from the accompanying drawnection therewith and with the pistons at substantially the outer -ends of their expansion strokes; Fig. 2. is a somewhat diagrammatical central longitudinal section of the engine, with parts in full and with the pistons shown at the ends of their` compression strokes; Fig. 3 is a diagrammatical view of the injection means, with the plungers in parallel relation in a common plane and with such yplungers in the relative positions which they have at the beginning of a compression stroke ofthe engine pistons; Fig. 4 is a fragmentary section on the line ll-Mn Fig. 3 showing the pump plunger adjusting means; Fig. 5 is a diagrammatical view similiar to that of Fig. 3 showing the relative position of the plungers when the engine pistons are near the end of a compression stroke and immediately before the fuel ejection charges takes place; Figs. 6 to 11 are different sectional views of an operative form ofthe fuel injection` means embodying the invention, with the parts corresponding to those in the diagrammatical Figures 3 and 5 and with Fig. 6 a vertical section on the line 6-6 in Fig. 7, with parts in full; with Fig. 7 a cross-section on the line i-l in Fig. 6, with a portion broken away; with Fig. 8 a vertical section on the line B- in Fig. 7, with parts broken away; with Fig. 9 a cross-section on the line 9-9 in both Figs. 8

and 10, with a .part broken away; with Fig. 10

a vertical section on the line I0-i0 in Figs. '7 and 11, with parts in full, and with Fig. 11 a cross- 'section on the line Ii-II in Fig. 10. Fig. 12 is a fragmentary sectional view lsimilar to Fig. 6 wherein the injection plunger is operated by high pressure air; Fig. 13 is a fragmentary sectional trigger plunger to retain it in raised or closed..

Referring to the drawings, A designates the fuel pump in which the invention resides, and B an engine of the free piston type with which the pump is associated.

The engine B (Figs, i and 2), whichis a more or less conventional showing so-that the operation of the fuel pump in connection therewith may be understood,`includes, as is common with such engines, a combustion chamber I3 and at each of opposite ends thereof a cylinder II, and at the outer end of each of these a direct bounce chamber I2 with the chambers I0 and I2 of approximately the same diameter and the cylinders I I of larger diameter. A pair of power pistons I3, I3 are mounted in opposed relation in the chamber I0, and each projects into the respective cylinder Il and carries therein an air compressor piston I4 with a, piston I5 projecting from its outer side into the associated bounce chamber I2. Each cylinder II is divide by its piston I4 into an air compressor chamber I6 at its outer end and a reverse bounce chamber I1 at its inner. end. The direct bounce chambers I2 are in pressure equalizing communication through a connection I3. The compressor chambers I6 are in outwardly opening check valve` communication with a scavenging receiver I9. The scavenging receiver I 9 has a port connection 23 with one end portion of the combustion chamber I0. so that it is uncovered by the ciosing piston I3 at the end of its power or expansion stroke,l An exhaust passage 2i is provided near the other end of the combustion chamber in position to be uncovered by its -closing piston I3 near the end of its power or expansion stroke, but before the opening of the scavenging port connection, as well understood in the art. Suitable check valve 'controlled air admission passages are provided for the chambers I 8 and I1, and an outwardly opening pressure relief valve is provided for the rebounce chambers. as well understood in the art.

A mechanical connection is provided between the two sets ofpistons to cause them to operate in unison. This connection, as illustrated in Fig, 1, includes a rack bar 23 projecting inward from each compressor piston at the outer side of the combustion chamber I and having respective driving pinion connection with a cam shaft 24 whereby such shaft is driven in one direction by expansion strokes of the pistons I3, I3 and in a reverse direction by the compression strokes thereof. A cam or eccentric 25 is mounted on the shaft 24, and the rotary reciprocatory movements imparted thereto by the inward and outward movements of the pistons are utilized to impart the movement to the mechanically operated parts of the fuel pump, as hereinafter described. Another form of operating connection between the piston rack bars 23 and the driven parts of thefuel injection means is illustrated in Fig. 18 and will be later described.

The fuel pump A, which is diagrammatically shown in Figs. 3 and 5, to facilitate an understanding of its operation and one practical embodiment of which isshown in Figs. 6 to 11, comprises a body or casing part 30 having bores 3|, 32, 33 and 34 therein in which respectively operate a pump plunger 35,3, timing plunger 33, a combination injection plunger and valve 31, and l. trigger valve 38 of plunger form. For convenience of description and understanding of the invention, these several plungers are shown in Figs. 3 and 5 as disposed with their axes in a common plane of the body casing 33, but this positioning and relationship can be varied, ex-

cept that the pump and timing plungers 35 and 35, which receive their actuation from the me chanical 'synchronizing connection between the sets of pistons, should, for simplicity of operating connections, have their axial movements in parallelism. For this purpose, the plungers 35 and 36 maybe flxediy connected at their outer ends by a cross-bar 39, which, in the present instance, has a push rod 40 (Fig. 1) projecting therefrom and in `spring thrust'engagement at its outer end with the peripheral face ofthe eccentric 25, This operating connection is such that the plungers 35-and 35 duplicate in a reduced degree the movements of the engine pistons, with the instrokes of the two plungers corresponding to the compression strokes of the power pistons, while the outstrokes of the plungers correspond to the expansion strokes of the power pistons. In Figs. 6 to 11 the pump and timing plungers 35 and 36 have their movements at right angles to those of the plungers 31 and 33.

The bore 3i for the pump plunger has a fuel inlet port 42 near its inner end, and such end is connected by a passage 43 through an outwardly opening check valve 44 to a charge chamber 45 at the inner end of the bore 33. The

pump plunger 35 cooperates with the fuel admission port 42 to regulate its closing in a wellknown manually or automatically variable manner upon an inward compression stroke oi the plunger, and then to open it. For this purpose, the inner end of the plunger is provided with axially spaced relief portions which successively register with the port 42 during movements of the plunger and are partially divided by a helical edged portion d6 which, in an inward movement of the plunger, moves across the port 32 and effects a gradual closing thereof. The period of compressing action of the plunger 35 takes place during the middle portion of its instroke and is regulated by a turning of the plunger, which may be accomplished manually, or in a governor controlled manner. by the movement of a rack bar 41 in engagement with a rack pinion 48 on the plunger (Fig. 4), as well understood in the art, thus regulating the amount of fuel pumped into chamber 45 at each stroke of plunger 35. At the time the pumping stroke takes place, the outlet of chamber 45 is closed, as will be hereinafter described, so that the fuel pumped into chamber 45 raises piston 31, and the measured fuel charge is thus ready to be forced out of chamber 45 when an outlet passage is opened.

The inner end of the bore 33 in which the injection plunger 31 operates is provided nearits lower end with a side recess 50 forming spaced outer and inner shoulders 5I and 52, respectively, and is connected by a passage 53 to a recess 54 in the Wall of the bore 34 in which the timing valve 33 operates, The plunger 31 is provided in spaced relation to its inner end with a recess 55 which, when the plunger 31 is at the limit of its inward movement, opens communication between the passage 53 and a relief passage 56 that connects the bore -53 with a side recess 51 in the wall of the bore 34, as shown in Fig. 3. The head or inner operating end of the plunger 31 has its opposing edges 53 and 59 spaced relative to the spacing of the recess edges 5I and 52 so that slightly after the edge 53 passes the edge 5I, in an inward movement of the plunger, the edge 59 will pass the edge-52, thus closing the passage 53 to the pressure chamber 45 and opening it to the relief passage 56 through the recess B5.

The outer end of the plunger 31 carries a piston 88 operating in a cylinder 8| of the body 38. -Thc chamber formed by 'the cylinder 8| at the outer side of the piston 88, in the present yembodiment ofthe invention, is in communication with the combustion chamber I8 of the engine through a connection 6-2, so that the pressure in the chamber 8| is substantially the same as that in the combustion chamber. As will appear later, `this pressure is relatively low when it opposes the pumping of fuel into cavity 85, but is relatively high at the time it forces fuel from that cavity. The diierence in areas of the piston 60 and inner end of the plunger 31 causes the pressure applied to the plunger to be materially increased in the charge chamber 45.

The trigger valve 38 has arecessed portion 85 which, when the valve is at and near the limit of its inward movement, cooperates with an endwise registering recess 88, in the wall of the-bore 3l, to open communication between the injection passage 53 and the injection passage 61, which latter leads to the fuel injector 68 for the combustion chamber I0, The valve 38`also has an elongated side recess 'l0 which crosses the adjacent end of the passage 58, when the'plunger is at or near the inner end of its stroke, and at the same time registers with a recess 'Hin the side wall of the bore 3l, which has communication with a return or drainage passage 12 in the body. It is thus evident that the passages 56 and 'l2 are in communication at approximately the same time that the injection passages 53 and 8l are in communication. This permits pressure relief or drainage to take place from the injection passages 53, 81 through passages 58, 12 when the injection plunger 31 is at thev inner end of its stroke.

The trigger valve 38 is provided at one end with a piston 18 Working in a cylinder 19 and at the outer side offsuch piston with a smaller piston 88 working in a cylinder 8|. The cylinder 19, at the outer side of the piston 18, has communication through a line 82 with one or both of the reverse bounce chambers of the engine, so that the rebounce pressure in said chambers is exerted against the piston 18 to force the trigger valve 38 inward. The outer end of the cylinder 8| is in communication with the combustion chamber i8 of the engine through the line 82 so that combustion chamber pressure is also exerted on the trigger valve to force it inward or to open position relative to the injection passages 53, 61. f The i the present instance, through the drainage line 12.

pistons 18 and 88 have the same relative areas'as the power and reverse bounce cylinders of the engine. It is thus apparent that the injection plunger 31 and trigger valve 38 are subjected to the combusion chamber pressures in proportion to the square of the diameters of theirrespective pistons 80 and 80, and that with respectto the trigger valve the rebounce pressure of the engine is also eiective to force it to its inward or injection position.

The timing plunger 38 projects at its inner end into a chamber 84 having an oil supply line 85 theretoin which an inwardly opening check valve 88 is provided. The oil in the supply line 85 is under a constant relatively low pressure. An oil supply passage81 leads from thechamber 84 or supply line 85 to the innerend of the bore 34 in which the trigger valve 38 operates and has a check valve 88 therein opening toward said bore. The chamber 84 also has a port or passage 89 in communication with the lower end portion of the bore 34 a short distance above the point of communication with -the bore of the passage 81.

This port 89 is so positionedrelative to the move ment 'of the trigger valve that it is closed when the valve is at the innermost point of its movement and is gradually opened as the valvel moves outward from such position as the side relief grooves 98 in the valveend move thereacross. These relief grooves also serve to open communication between the chamber 84 and a safety relief passage 9| in the body 38 should the chamber pressure be suicient to move the valve to the limit of its outward stroke. The passage 9| connects with the drainage passage '|2. A slow regulated leakage of oil from the chamber 84 is permitted through the passage 92 controlledby a needle valve 93. This passage has return drainage connection with the source ofv oil supply, in

An inward movement oi the plunger 38 produces a displacement pressure in the chamber 84 acting first through the passage 81 and then through the port 89 against the inner end of the trigger valve 38 to move it to its outward position (Fig. 5) against the pressures in the piston chambers 19 and 8|. The pressure in the ychamber 84 is controlled by the speed of movement of plunger 38 and the rate of leakage from the throttle port 92. Near the enci of the engine compression stroke, its piston velocity decreases, and the velocity of the lplunger 36, which has a movement corresponding to the ,engine piston movement, accordingly decreases, so that it is no longer able to maintain pressure in the lchamberv 84 against the leakage occurring through port 92. In this manner the outward pressure against the inner end of the trigger valve 38 is also decreased. At the same time the pressures in chambers l'|9 and 8|, in communication, respectively, with the rebounce and combustion chambers of the engine, are rapidly increasing. At a particular'point in the stroke, determined by the degree of opening of the throttle port 92, the gas pressure in said chambers `li'i and 8| overbalances A the fluid pressure acting against the inner end of the trigger valve and the valve thereupon moves inward in a rather rapid manner. When the inner edgeof the valve recess 85 passes the outer edge of the bore recess 54, the valve is moving at a high velocity, so that the injection passage 53 is quickly opened to the passage 8l. The `fluid under high pressure invchamber 85 is thus quickly released to the fuel injection valve 88 and an injection of a fuel charge into the combustion chamber is effected by the inward movement of plunger 3l due to the pressure in chamber 8|.

This inward movement of plunger 3'| resulting from pressure in chamber 8| continues until shoulder 88 thereon clears shoulder 5|, thus opening communication between the injection passage 53 and relief passage 56. At this point in the operation, both the injection plunger 31 and the .trigger valve 38 are at the ends of'etheir inward strokes (Fig. 3) and relief communication is established between the injection passages 81 and 53 and the drainage passages 56 and 12. The

-sudden relief of pressure thus effected at the end of an injection reduces the te'ndency of the fuel nozzle tofdribble. After injection, the ensuing explosion occurring in the engine moves the engine pistons outwardly, thus withdrawing plung- Aers 35 and 36 and allowing relling of chamber i 84 and the raising of pump piston 35 in position for anotherpumping stroke. The oil is supplied atfmoderate constant pressure to the inlet passages 42 and 85 by means of a pump |00 through a line A return line I 02 is provided tothe pump from vthe drainage passage 12. The quantity of fuel delivered upon the injection stroke of the plunger 35 depends on the `p sitlon of the helical groove on such plunger in relation to the inlet port 42. p

In Figs. 6 to 11, which illustrate a practical and operative Aembodiment of the invention, the reference characters, exceptthat each includes a prime exponent, correspond to those in the diagrammaticalvview in Figs. 3 and 5, and designate the same parts, chambers and passages,

the power and reverse bounce cylinders.

, the stroke independent of the stroke or piston and the arrangement and operation thereof will be understood fro ing the description.

In the operation of this fuel pump, it will be understood that the movements of the plungers 35' and 3E are in exact duplication of the movement of the working pistons of the engine, except only that the motionofthe plungers is reduced. During a compression stroke of the engine, the plunger 35' forces a measured quantity of fuel into the cavity 45' against the inner end of the injection valve 31' to force lt outward against the pressure in the chamber 6I from the position shown in Fig. 3 to that shown in Fig. 5. At the same time, the plunger 36' moves into the fluid chamber 84' to increase the pressure therein and cause it to act through the passage 8l against the inner end of the trigger valve 38' to initially raise it to a position where the fluid pressure can also act on it through the port B9' to move it to the outer end Aof its normal stroke (Fig 5). This movement of the valve closes the communication between the injection passages 53 and 6l and the drainage passages 56 and 12'. Escape of fluid pressure from the chamber 84' is the foregoing without repeatpermitted at a predetermined" rate through the As the engine pisvalved metering port 92'. tons approach their compression termini, a rapidly increasing pressure develops on pistons 60', 18' and 80' by virtue of the increase in the compression and rebounce pressures of the engine. The plunger 31', however, is retained against this mounting pressure on its piston 60 by means of the hydraulic lockexisting in chamber 45 due to the check valve 44' and the closing of passages 53 and 56'. As the timing plunger 36' nea-rs the end of its compression stroke, its movement is slowed down so that the leakage through -port 92 then exceeds the displacing action oi the plunger and this permits the increasing forces on the pistons 18' and 80' to force the trigger valve inward to connect the injection passages 53' and 61'. As these passages are uncovered, the hydraulic lock in chamber 45' is relieved, thereby permitting the pressure exerted on the injection plunger 3'1 to effect a rapid inward movement of the plunger and the sudden discharge of a metered quantity of fuel from the chamber 45 through said open passages to the injection nozzie.

The fuel injection means is arranged and adjusted so as to make injection occur at substantially the same relative part of the piston stroke of the engine independent of the speed, the stroke, the quantity of fuel injected, or the pressure. This is accomplished as follows: With drainage passage Bl' closed oil, the pressure in chamber 84' will be proportional to the square of the instantaneous piston speed which is proportional to the mean piston speed. The mean piston speed is approximately proportional to the square root of the sum of the combustion pressure, times area or combustion cylinder, plus reverse bounce presvelocity. The exact point at which the trigger valve 38' begins to move ls fixed by the adjustment o! the leakage at 82'. and the smaller the opening at 92' the nearer will the engine pistons be to dead center position when said valve moves inward. After the trigger valve starts to move, an appreciable time, of the order of' two milseconds, is required for injection to occur. This time is inversely proportional to the piston speed. Injection. therefore, occurs at the same relative part of the stroke independent of piston velocity. Injection may be made to occur directly at the end oi the stroke although an earlier injection will generally be desirable. If it is desired that with higher speeds injection should occur earlier in the stroke, a compensating spring S5 may be placed in the bore 3d under the trigger valve 38' and made adjustable as to tension by a screw 96', as shown in Fig. 14. The injection pressure is proportional to the pressure acting on the lnwardly moving injection plunger 3l', and the duration of injection is determined by the injection pressure and the size oi the orifices in the injection valve 88'. which valve may be of any suitable type and need not, therefore, be specifically described.

In the construction described, the pressure in cylinder El varies with that in the combustion chamber, and increases when the combustion chamber pressure increases, thereby making the speed of injection vary with the pressure in the combustion chamber. Also the pressure in chamber 6i' is less at the time the pumping operation of plunger 35' is forcing plunger Sloutward than when plunger 31' is. ejecting the fuel. This ls a desirable relation, but it will be understood that an approximation to the same results could be made by utilizing a constant pressure on plunger 3l' in any desirable wanas for instance by high pressure air, as indicated in Fig. 12.

Likewise, while the arrangement described for operating trigger valve 38' effects a desirable automatic control, fairly good results might be obtained throughV timing plunger 36 even though one of pistons 18,' or 80' was omitted, or one or both operated by constant pressure.

-It is apparent that the pump plunger 35' forces a metered quantity of fuel into the charge chamber 45 against a yielding ejecting pressure exerted by the plunger 31'; that said chamber is in valve-controlled communication with the fuel injection nozzle of the engine; that the control valve 38' for said communication is held in closed position by pressure generated in the oll chamber 84 by an inward stroke of the plunger 36' which is effected by the compression stroke of the engine pistons simultaneous with the pumping stroke of the plunger 35'. and that said valve is moved inward to open position by increasing fluid pressures generated in the engine during the compression strokes of its pistons, coordinated with a timed release of pressure from the chamber B4 through the controlled port 92' due to decreased speed of the plunger 36'. It will be understood that the timeo! injection of a charge with respect to the .end of the compression stroke is dependent on the adjustment of the relief valve 93', and that the greater the relie! opening the earlier will be the lnlection during the compression stroke of the engine pistons, and vice versa.

In Fig. 13, the application of fluid pressure to the trigger valve to move it to open position against the pressure in the chamber 04 (Fig. 8) is through separate pistons and a lever, with the pistons acting -at diierent longitudinally spaced points on the lever. In this form pistons 80" and 18", corresponding to pistons 80 and 18, respectively, in the first form, operate in cylinders 8|" and 79", respectively, with the former connected to the combustion chamber of the engine or to some other` suitable source of uid pressure supply, and the latter communicating with the reverse bounce space II of the engine. The stems of the pistons act against a lever I I0, fulcrumed at within the body part 30", with the point of application of force of the piston 80" closer to the lever fulcrum than that of the other piston. In this manner, the operating forces acting through the pistons and lever may be proportioned, as desired. A piston actuated movement of the lever is communicated to the trigger valve through an interposed compression spring ||2. Movement of the lever is retarded by a plunger ||3 connected to the lever and operating in a pot ||4 with oil therein flowing slowly from one side to the other of the plunger, thus reducing the tendency of lever H to iiutter during operation.

In Fig. 15 is shown a modification of the fuel pressure means operating on the trigger valve or plunger in opposition to the fluid pressure in the pressure chamber H9 to which'the outer end oi` the trigger valve, marked |20, is exposed. A check valve |2| opening toward said chamber is disposed in said passage. The inner end of the plunger IIE serves as a valve for controlling admission of oil under predetermined pressure, for instance that from the outgoing side of the pump |00 to .the chamber H9, through a passage |22. The passage |22 is closed to the inner end of the bore H0 by the plunger H5 except during an intermediate portion of its stroke. The chamber H9 has a pressure relief passage |23 controlled by a needle valve |24. A cylinder |25 has a piston I 26 therein which is acted on at one side by pressure in the chamber H9 through a passage |27 and at its other side by a spring |28 in a cylinder |29.

It is apparent that with the use of this form. variable timing is effected by means of plunger IIE which pumps a fixed quantity of oil into the chamber I9 at each instroke of the plunger, and consequently of the engine pistons. The needle valve |24 isso adjusted as to allow an equal quantity oi oil to that pumped to escape from the chamber ||9 during a pumping cycle of plunger when the engine is operating at predetermined reduced speed. Upon an increase of engine speed. the faster pumping action of the plunger I|5 tends to increase th'e pressure in chamber |25 and to push the piston |26 outward against the pressure of the spring |28. The resulting increased pressure effected by spring |28 causes the trigger valve I 20 to react more quickly to the pressure balance in chamber 84, thus escaping past the valve |35 into lthe leakage line |5| from the pressure chamber 84, and that dur-- eiiecting an earlier inward movement of the trigger valve |20 against the pressure in the vtiming chamber and a consequent earlier charge in- Jection. y The pressure will not continue to increase in chamber |20 for a set speed, as the instantaneous iiow of oil past valve |24 is a function of this feature. Thus, the pressures existing upon the trigger valve |20 are a direct function of the engine speed. Any oil pressure escaping around piston |26 is relieved through a passage |29 leading to the relief passage |23 at the outer side of the valve |24.

In thermodification shown in Fig. 16, the iiuid pressure acting on the trigger valve or plunger in opposition to the iiuid pressure in the timing chamber 04 is eliminated and a compression spring of predetermined tension substituted therefor. In this modification, |30 designates the trigger valve and |3| a coiled compression spring set into a cylinder |32 and acting against the outer end of said valve at a `pressure which is less than the maximum pressure created in the chamber 04 during an instroke of the timing i plunger and is greater than the pressure in said chamber when the timing plunger speed is slowing up at the endof said stroke. i Thus, thctrigger valve is moved to closed position against the tension of the spring |3I when the maximum pressure is present in chamber B4 and is moved by the spring to open injection position when the spring pressure overbalances the timing chamber pressure immediately before the end of the instroke of the timing plunger.

In Figure 1'7 is shown a modification whereby adjustment of the relief valve for the timing pressure in chamber 84 isl automatically responsive primarily to the maximum fluid pressures generated in the working cylinder and rebounce cylinders of Athe engine. This function automatically controls the timing with reference to the peak pressures existing in the above chambers. In this modication the relief valve for the timing pressure chamber at is designated i 35 and is attached to a piston |36 operating in a cylinder |61 in th'e body, here designated |38.

The piston |34 at its outer end carries a larger piston |39 operating in a cylinder |40 against a valve closing spring |4| at its outer side, the tension of which spring is adjustable by a screw member |42 in the body part. The cylinder |37 at the inner side of the piston |36 has communication withthe combustion chamber of the engine through a passage I 43, which may constitute a branch of the passage 62 disclosed in the rst illustrated form. An inwardly opening check valve |44 is provided inthe passage |43, and a leak by-pass |45 is provided around said valve and has a needle control valve |46 therein. 'Ihe cylinder |40 at the inner side of its piston has communication with the rebounce pressures of the engine through a passage |41, which may constitute a branch of the passage 82 of the first illustrated form. An inwardly opening checkv valve |48 is provided in the passage |41 and a leakage by-pass |49 is provided around such valve and has a needle control valve |50 therein.

In the operation of this modification (Fig. 17), in connection with any of the various fuel injection means and modifications illustrated, it will be understood that during an inward stroke of the pump plunger (3B in the rst form), oil is ing the major portion of such stroke, such escape is less than the pressure build-up in the chamber aymara ll 3l, so that the trigger value of the associated form is thereby moved to closed position against the opposing forces acting thereon. When the speed of-movement of the timing plunger begins to slow down at the end of its instroke. the pressures existing in chambers |31 and |50 are such as to maintain a predetermined opening of the reliefpassage from chamber` 84. Due to the reduction of velocity of the timing plunger 36, the rate of relief from chamber 8i relative to the displacement of the plunger has increased, whereby opening movement of the trigger valve is permitted. It is thus apparent that the rate at which thefoil is allowed to flow from the pressure chamber 84 through the relief passage is a function of the current maximum engine compression pressure exerted on the piston land of the maximum current rebounce pressure exertedon the piston |39. .These pressuresare maintained at a relatively steady value by means oi' the restricted leak-olf valves |48 and |50 in the respective bypasses around the check valves i and |43, and pressure variations on the pistons |38 and |39 are therefore allowed only as the peak pressures of the combustion and rebounce chambers vary. 'I'hese pressures are resisted by spring |4| which tends crease on their compression strokes, and means tending to start the fuel ini ection by a force vwhich chamber to said nozzle when the valve is open,

to force the valve |33 into its closed position.

As the speed of the engine increases, the pressures exerted under pistons |38 and |39, and particularly the latter, increase, and this effects a relatively greater opening oi valve |35, thereby al lowing a greater quantity of oil to escape which permits an earlier movement of the trigger valve relative to the inner terminal position of the timing plunger and a consequent earlier injection of a fuel charge into the cylinders with regard to the combustion end of the piston compression stroke. As. the speed of the unit decreases, the natural reduction of pressures under pistons |35 and |39 tends to cause a reverse timing action to occur.

In Fig. 18 is shown a different connection from that illustrated in Fig. 1 for communicating mo.- tion from the engine synchronizing mechanism to the pump and timing plungers 35 and 38 of the fuel injection means. In this form, 24 is the driven shaft of the synchronizing mechanism, being driven by pinion connection with the rack bars 23 projecting from the opposing pistons. This shaft carries a pinion |55 in lieu of the eccentric 25 of Fig. 1, and this meshes with and imparts rocking movements to a segmental rack |58 that has a stationary fulcrum |51 on a convenient part of the engine frame. A link |38 is pivotally connected at one end to the segment |56, intermediate its fulcrum and rack portion, and

at its other end to the cross bar 39 connecting the pump and timing plungers 35 and35, so that reciprocatory movements of the segment will impart corresponding movements to said plungers.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of numerous modifications and changes without departing from the spirit of the claimsl Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

1. In an internal combustion engine of the free piston type having means for injecting fuel into the cylinder of the engine. means for timing the fuel injection with the timing varying in accordance with variations in the stroke of a working pisto'n of the engine comprising means opposing the start of fuel injection with a force decreasing as the speed of the engine pistons deand means for timing the opening of the valve and causing the time of injection to vary in accordance with variations in the stroke of a working piston ofthe engine, comprising means tending to open the valve and a device connected with at least one of the engine pistons Vand opposing the opening of the valve with decreasing force as the speed of the engine pistons is reduced in nearing the end of its compression stroke.

3. In an internal combustion engine oi the free piston type having a fuel injection nozzle, fuel control means comprising a fuel charge chamber, means providing a passage from the chamber to the nozzle, a valve controlling said passage, means for forcing a charge from said chamber to said nozzle when the valve is open, and means for' timing the opening of the valve and causing the time of injection to vary in accordance with variations'in the stroke of a working piston of the engine and comprising means opposing the opening of the valve, and means tending with increasing force to open the valve as the engine pistons approach the end of the compression stroke.

35 4. In an internal combustion engine of the free piston type having a fuel injection nozzle, fuel control means comprising a fuel charge chamber, means providing a passage from the chamber to the nozzle, a valve controlling said passage, means for forcing a charge from said chamber toy said nozzle when the valve is open, and means/for timing the opening of the valve and causing the time of injection to vary in accordance with variations in the stroke of a working piston of the engine, comprising a fluid chamber having a controlled leakage opening, a plunger connected for movement proportional to the movement of the engine pistons and moving into said fluid chamber during the compression stroke of the engine pistons, and means directing the pressure in said fluid chamber to move the valve to closed position and opposing a pressure that does not decrease during the compression stroke of the engine and which tends to open the valve.

5. In an internal combustion engine of the free piston type having a fuel injection nozzle, fuel control means comprising a fuel charge chamber, means providing a passage from the chamber to the nozzle, a valve controlling said passage, means for forcing a charge from said chamber to -said nozzle when the valve is open and means for timing the opening of the valve and causing the time of injection to vary in accordance with variations in the stroke of a working piston of the engine, comprising a fluid chamber having a controlled leakage opening, a plunger connected for .movement proportional to the movement of the engine piston and moving into said fluid chamber during the compression stroke of the engine pistons, means directing the pressure in said fluid chamber to move the valve to closed position, a cylinder and piston therein, connections from the cylinder to the compression chamber of the engine, and connections from said last piston to the valve whereby movement of the piston in response ber with a controlled leakage opening, a timing v plunger movable into and out of said chamber,

connections between the timing plunger and. the

engine pistons to movethe timing plunger proportionately with the engine pistons and into said fluid chamber during the compression stroke of the engine pistons, means directing the pressure in said uid chamber to oppose the opening of said valve, a cylinder and piston connected to the valve and tending to open the valve when there is pressure in the cylinder, means connecting the cylinder to the compression chamber of the engine. and another cylinder and piston also con-` nected with the valve and tending to open the valve when there is pressure in the last said cylinder, and a connection from the last said cylinder .to the rebounce chamber.

7. In an internal combustion engine of the free piston type having metering means for injecting fuel into the cylinder of the engine including an injection valve movable to closed and open injection positions, means acting to normally hold the valve in open position and yieldingly resisting its movement to closed position, and fuel injection timing means including a uid pressure feature acting against said valve in opposition to said first means and a fluid displacing feature, said last feature being operable by the engine pistons during a portion of their compression strokes to increase said fluid pressure to move the valve to closed position against the pressure of said first means, said timing means also including a feature which automatically reduces its fluid pressure sumcient to permit the valve to move to. open injection position when the engine pistons are near the ends of their compression strokes.

8. An arrangement as called for in claim 7 wherein the pressure reducing feature of said timing means operates during the speed changing period of movement of the engine pistons when near the compression ends of their strokes to permit the valve to move to open injection position beforeV the completion of the said compression strokes.

9. An arrangement as called for in claim 7 wherein the pressure reducing feature of said timing means includes a pressure relief means which is responsive to iiuid pressures generated by the engine during a compression stroke of its pistons and which operates to reduce the'valvel closing pressure of said timing means belowthe opening pressure of said first means during the speed changing period of the engine pistons when near the ends of their compression strokes, said pressure relief means being regulable to vary the opening time of the valve relative to the depending engine pressures.

10. In an internal combustion engine of the free piston type-having metering means for injecting fuel into the cylinder of the engine including a trigger valve movable to closed and open injection positions, means normallyholding the valve in open injection position and yieldingly resisting almovement of the valve to closed position, the action of said last means being responsive to fluid pressures, one at least of which is automatically increased during the compression 'strokeof the engine pistons, andi fuel injection,

timing means including a iiuid pressure feature acting against said valvein` oppositionl to said first means and a fluid displacing feature, said last feature being operableby the engine pistons during a portion of their compression strokes to increasefsaid fluid pressure to move the valve to closed position againstthe pressure oi said rst means, said timing means including a bleed member which automatically reduces its uid y'pressure sufdcient to permit the valve to move to open injection position during the' speed changing movements of the engine pistons when near the ends of their compression strokes.

11. In an, internal combustion engine of the free piston type having metering means for injecting fuel into the cylinder of the engine including a trigger valve movable to closed and open injection positions, means normally holding the valve to open injection position and yieldingly resisting a movement of the valve to closed position, said means being responsive to fluid compression pressures generated .by the engine during a com'- pression stroke of its pistons and which pressures increase during said strokes, and fuel injection timing means including a iiuid pressure feature acting against said valve in opposition to said iirst means and a fluid displacing feature, said last feature being operable by the engine pistons during a portion of their compression strokes to increase said fluid pressure to move the valve to vclosed position against the pressure of said first means, said timing means also including a bleed member which automatically reduces its iiuid pressure sulcient to permit the valve to move to open injection position when the engine pistons are near the ends of their compression strokes.

12. In an internal combustion engine of the free piston type having metering means for injecting fuel into the cylinder of the engine including a trigger valve movable to closed and open injection positions, means normally holding the valve in open injection position and yieldingly resisting its movement' to closed position, and fluid injection timing means including a iiuid pressure feature acting against said valve in opposition to said first means and a fluid displacing feature, the latter operable by the engine pistons during a portion of their compression strokes to increase said fluid pressure to move the valve to closed position against the pressure of said first means, said timing means including a relief passage and a regulable control valve therefor to permit an escape of fluid pressure from said timing means topermit said first valve to move to open position when the engine pistons are near the ends of their compression strokes and before completing such strokes.

13. In an'internalA combustion engine oi the free Piston typehaving meteringy means'for injecting fuel into the cylinder ofthe engine in- `cludinga trigger valve movable to closed-and open injection positions,v means normally holding the valve in open' injection position and yieldingly resisting its movement tov closed position, said'v means including a fluid pressureactuating' force which automatically increases throughout at least a portion o'f the length -of the compression stroke of thel engine pistons, and fuel injection timing means including a iiuid pressure feature acting against said valve in opposition to4 saidl firstv means and a uid displacingfeature, the vlatter Y beingioperable by the engine pistons during a vportion of their .compressionA strokes to increase f mais said fluid pressure to move the valve to closed position against the pressure of said first means. said timing means having a 'pressure relief feature which cooperates with the increasing pressure of said first means to overhalance said timing means pressure and effect a quick movement of the valve to open position during the last portion of a compression stroke of the engine pistons.

14. In an internal combustion engine of the free piston type having metering means for injecting fuel into the cylinder of the engine including a trigger valve movable to closed and open injection positions, means normally holding the valve in open position and yieldingly resisting its movement to closed position, said means increasing in pressure during each compression stroke oi' the engine pistons. and fuel injection timing means including a iluid pressure means acting on said valve and pressure during a compression stroke of the engine pistons to move the valve to closed position and then during the speed changing movement of the pistons near the end of the compression stroke acting to decrease said pressure to permit a movement of the valve to open position,

15. In an internal combustion engine of the free piston type having a fuel injection nozzle with a fuel passage thereto and a valve normally closing the passage and operable to open the passage and permit fuel injection, a member connected to a working piston of the engine to reciprocate in synchronism therewith, and means for opening the valve controlled by reciprocation of the member and comprising means to adjust the timing of the opening of the valve automatically to bring it into predetermined relation with the end of the compression stroke of the piston when the length of the stroke is varied.

16. The method of timing fuel injection in an Y internal combustion engine of the free piston type, which comprises determining the time of injection by the time when a `pressure from the compression chamber of the engine during a compressionstroke overcomes a pressure resisting fuel injection, .which latter pressure decreases with the decrease of the speed of a piston of the engine on its compression stroke.

17. 'Ihe method of timing fuel injection in an internal combustion engine of the free piston type and provided with a rebounce chamber, which comprises determining the time of injection by the time when the rebounce pressure on a compression stroke of the pistons overcomes a pressure resisting fuel injection, which latter pressure decreases with the decreasing speed of the pistons as they near the ends of their compression strokes.

ing a chamber having an inwardly lopening check valve controlled communication with a fluid pressure supply source and also having a controlled pressure bleed outlet. means operable by the engine pistons to increase the pressure in said chamber a predetermined extent to move the valve to closed position during a compression stroke of the pistons, and means operable by a predetermined compression pressure of the engine to yieldingly oppose movement of the valve to closed position means movableagainst. its pressure by a charge pumped into the chamber and operable by its pressure to cooperate with the charge pressure to eject a fuel charge' from said chamber and throughsaid passage when the latter is open, and means timing the opening of said valve in accordance with the slowing-down of the engine piston on a compression stroke preparatory to reverslng their movements.

2l. In an internal combustion engine of the free piston type having a fuel nozzle and a fuel injection passage thereto, a valve operable to open and close said passage, means forming a chamber in communication with said passage, a plunger movable to force a.A charge from said chamber through said passage when open, means to pump a charge of fuel into said chamber and preventing its return and to force the plunger to retracted position, fluid pressure means yield- 1 REFERENCES CITED The following references are of record in the file of this patent:

18. The method of timing fuel injection in an\ 1 internal combustion engine of the free piston type and provided with a reliounce chamber, which comprises determining the time'of injection by the time when pressure from the rebounce chamber and the compression chamber of the engine on a compression stroke of the pistons overcomes a pressure resisting fuel injection, which latter pressure decreases with the decreasing speed of the pistons as they near the ends of their compression strokes.

19. In an internal combustion engine of the free piston type having a fuel injection nozzle. a fuel injection passage thereto, and 'a valve operable to open and close said passage, means form- UNITED STATES PATENTS Number Name Date 998,463 Butsch July 18, 1911 1,897,044 Elwell Feb. 14, 1933 2,064,976v Jahnicke Dec. 22, 1936 2,163,313 Voit June 20, 1939 2,246,701 Steiner June 24, 1941 2.344.058 Pescara Mar. 14, 1944 FOREIGN PATENTS Number Country Date 427,668 Great Britain 1935 475,730 Great Britain -f Nov. 24, 1937 509,111 Great Britain n n.- July 11, 1939 210,884 Switzerland 1940 OTHER REFERENCES Hurst (A. P; C. PJ, Ser. No. 348,726, pub. May 11, 1943.

? Certicte of Correction 18 Patent No. 2,447,513. August 24, 1948.

FRANK M. LEWIS It is hereby. certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 17, for the Word charges read charge; column 3, line 19, for divide read divided; column 5, line 57, for oombusion read combustion; column 7, line 36, for 67 read 67'; column 15, line 20, after and;nsert a plunger feature the latter connected to a piston 0j the engine and operable to increase the fluid; and 'that t e said Letters Patent should be read with giese coorrfctions therein that the seme may conform to the record of the case in the atent ce.

Signed and sealed this 9th day of November, A. D. 1948.

l [me] l THOMAS F. MURPHY, l

Assistant ommz'ssoner of Patents. 

